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Title: In-situ characterization of the optical and electronic properties in GeTe and GaSb thin films

GeTe and GaSb thin films obtained by pulsed laser deposition were investigated by spectroscopic ellipsometry at controlled temperatures. The GeTe films were fully amorphous, while the GaSb films were partially crystalized in the as-deposited state. The Tauc-Lorentz model was employed to fit the experimental data. From the temperature study of the optical constants, it was observed the crystallization in the 150–160 °C range of GeTe amorphous films and between 230 and 240 °C of GaSb amorphous phase. A second transition in the resonance energy and the broadening parameter of the Lorentz oscillator was observed due to the crystallization of Sb after 250 °C. The temperatures of 85 °C and 130 °C are noticed as the start of the relaxation of the amorphous GeTe phase and as-deposited GaSb. The peaks of the imaginary part of the dielectric function red shifted after the phase change, while the variation with temperature of the crystalline phase follows the Varshni law. The electron-phonon coupling constants are 2.88 and 1.64 for c-GeTe and c-GaSb, respectively. An optical contrast up to 60% was obtained for GeTe films and a maximum value of 7.5% is revealed in the case GaSb, which is altered by the partial crystallinity of the as-deposited films.
Authors:
; ;  [1] ;  [2]
  1. National Institute of Materials Physics, Atomistilor 105 bis, RO-077125 Magurele, Ilfov (Romania)
  2. National Institute for Laser, Plasma and Radiation Physics, Atomistilor 409, RO-077125 Magurele, Ilfov (Romania)
Publication Date:
OSTI Identifier:
22492796
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 118; Journal Issue: 13; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; AMORPHOUS STATE; CRYSTALLIZATION; ELECTRON-PHONON COUPLING; ELLIPSOMETRY; ENERGY BEAM DEPOSITION; GALLIUM ANTIMONIDES; GERMANIUM TELLURIDES; LASER RADIATION; PULSED IRRADIATION; RED SHIFT; RELAXATION; RESONANCE; THIN FILMS